Friction joint



July 20, 1954 KROHM 2,684,261

FRICTION JOINT Filed May 12, 1948 INVENTOR. FRED A. K/FOHM WX/W ATTORNEY Patented July 20, 1954 UNITED sures FRICTION JOINT g 2 Claims. 1

This invention relates to mirrors and other accessories adapted for use outside the body of a vehicle and supporting devices therefor and particularly to a novel construction and arrangement designed to facilitate the installation and use thereof.

An object of the invention is to provide an improved vision device with resilient means adapted to facilitate assembly of parts and to hold parts of the assembly securely in operative relationship without the necessity of manufacturing such parts to difficult and costly manufacturing tolerances.

Another object of the invention is to provide an improved mirror device for positioning the mirror and frame therefor in angular adjustment with respect to the vehicle and for maintaining the selected position.

Another object of the invention is to provide a mirror device with an improved universal joint connection between the mirror member and the supporting arm therefor whereby the mirror member may be angularly adjusted in any plane with respect to the supporting arm and be maintained in the selected position.

Another object of the invention is to provide a mirror device with an improved rotatable universal friction joint of simple, efficient construction to maintain the mirror in a selected position.

Another object of the invention is to provide a i rotatable friction joint in which the friction members allow rotation under predetermined frictional resistance and frictionally prevent axial displacement under operating conditions.

Another object of the invention is to provide 'a rotatable friction joint in which the frictional resistance to axial movement after assembly is in excess of the frictional resistance to axial movement in the assembling operation.

This application is a continuation in part of my copending application Serial No. 792,478, filed December 18, 1947, now abandoned.

two modified spring friction members shown in Figures 2, 5, 6 and 7;

Figure 5 is an enlarged transverse sectional view of the rotatable friction joint taken substantially as indicated by the line 5--5 of Figure 2;

Figure 6 is an enlarged transverse sectional view of the rotatable friction joint taken substantially as indicated by the line E-t of Figure 2;

Figure 7 is an enlarged vertical sectional View showing the method of assembling the spring friction members, the connecting member and the mirror supporting arm;

Figure 8 is a view of another form of a rotatable friction joint interposed between -a supporting arm and a mirror member; and

Figure 9 is a sectional view of an additional form of a universal joint connecting a mirror member and a mirror supporting arm.

Conventional ball-and-socketjoints are notoriously difficult to hold in a predetermined position in service. The frictional contact usually is limited and it is diificult to apply to the contact a predetermined and adequate spring pressure which "can be maintained without fatigue. This is particularly important in side-view mirrors subjected to car vibrations; The conventional ball-and-socket joint is of course vulnerable to such vibrations regardless of their direction, since in the conventional universal joint when relied upon singly there is but one frictional contact depended upon for the universal movementpthe universality of the joint, which gives it utility, also exposes it, with equal universality, to vibrations, regardless of their direction. 7

The universal friction joint andparts thereof exemplified in Figures 1 through 7, comprises a friction hinge joint and a rotatable friction joint.

The friction hinge joint includes -a bifurcated integral hinge member i114 with a circular exterior abutting flange I95 and a reduced circular axial portion I06 extending through a suitable opening in the rear wall I01 of the shell carrying the mirror and is secured thereto against relative movement by an upset flange H13 bearing against a Washer I09 to clamp the rear wall I07 of the mirror shell between the exterior flange H35 and the washer Hi9. This Washer is preferably of a relatively large size and serves in the dual capacity of reenfor'cing the shell and as 'a friction element to assist in preventing relative movement between the hinge and shell.

The bifurcated member m l of the hinge joint comprises furcations or legs H9 and ill forming a straight sided slot H2 which receives a cemplementary round fiat tongue H3 of a fitting H4. The exterior surfaces of the legs are preferably of a curvature corresponding to that of the tongue portion so as to form a generally spherical head or knob. The hinge member and fitting are connected by a rivet or pintle 1 id for pivotal movement about an axis at right angles to the longitudinal axis of the upper extremity of a curved mirror supporting arm Ht. A lower end of the supporting arm H6 is provided with a suitable clamp whereby the mirror can be easily and quickly attached to a vehicle door. The leg MB is provided with an aperture ill and the tongue portion 1 l3 with an aperture i l8 of a diametrical size corresponding to aperture ill to receive a shank portion N9 of the rivet. The other leg iii is provided with an aperture 529 of a size somewhat less than apertures ill and H8 and receives a reduced portion m of the rivet. The apertures Ill and i2!) are preferably countersunk in order that the ends of the rivet may be upset in the countersinks and conform to the general curvature of the spherical head to present a pleasing design. One side of the tongue H3 is preferably provided with an annular recess 122 within which is disposed a friction cup washer 523 for concealment with a portion of its convex face engaging the planar surface on the leg ill. With this arrangement the clamping pressure, principally between the planar surface of the leg H and tongue H3, may be predetermined to maintain the mirror member in any desired angular position, within its range of pivotal movement, with respect to the fitting H4. Obviously, a pair of washers in lieu of one could be employed, and if found desirable, a screw could be substituted for the rivet H but the device would not be theftproof. The parts may be reversed so that the hinge member m4 may be provided with a tongue and the fitting lid with a bifurcation. Furthermore, the recess for the washer could be provided in the leg Ill instead of in the tongue, or in both.

The rotatable friction joint between the fitting and arm will now be described. The fitting HA, which constitutes a component of the hinge joint, is preferably constructed of stainless steel and includes an integral slightly tapered portion 12% provided with a cylindrical bore, socket, or cavity E25 which receives the upper extremity of the supporting arm H8 as illustrated in Figure 2. The Wall of the bore is generally rough due to the annular serrations or ridges that result from the boring operation, and this factor may be taken advantage of as will be subsequently described. The design of the portion i72 is in harmony with the remainder of the fitting and the hinge member to enhance the general overall appearance of the joint.

The supporting arm H6 is preferably bent to an arcuate shape and is preferably solid and round in cross-section throughout its entire length. Its upper extremity is grooved to form a reduced cylindrical portion or neck l2ll. This neck is spaced inwardly from the pilot end E2? of the arm and terminates in a pair of shoulders i228 and 52%. The end I2! is chamfered as depicted so as to assist in guiding the arm into the bore. The neck portion 126 is of a length somewhat less than the depth of the bore so as to conceal a plurality of corresponding friction producing members 536 associated with the parts. The members 1% are preferably constructed of some desirable resilient material, such as bronze, and are generally semi-cylindrical in shape as shown in Figure 4. Each member includes a pair of substantially identical arcuate end bearing portions llii and i122 of a curvature substantially corresponding to the curvature of the cylindrical neck portion I26 of the arm so as to normally engage the neck through the arcuate lengths of the bearings. The end bearings more or less constitute circular ring sections. Each resilient member also includes a bearing portion E33 intermediate the end bearings. This intermediate bearing is of a size larger than the end bearings and is preferably generally arcuate in cross-section and more or less curved or elliptical in longitudinal section.

As exemplified in Figure 7, the parts are assembled by placing the friction producing mem bers H39 about the neck H28 and then inserting the pilot end iii of the arm and the end bearings list of members 1 3E; into the bore I25 of the fitting Ht, whereupon the arm and members are pressed or rammed with considerable force into the assembled position with the fitting as depicted in Figure 2. The shoulder I29 on the arm serves as an abutment for the resilient members we as the arm is driven into place and the inward movement of the arm is limited by the pilot end of the arm engaging the end wall of the bore. It will be noted that the cylindrical space about the neck within which the friction members are arranged is of a size sufiicient to permit such members to be distorted when rammed into the bore F25. The cylindrical portions of the arm adjacent either end of the neck 52% finds support on the Wall of the bore I25 to provide a well stabilized construction.

As the parts are being assembled the intermediate bearing portions l33 are compressed to cause distortion and elongation of the members to an extent whereby the end bearing portions i3! and H32 will bend outwardly so that the end arrises thereof will intimately engage the bore at areas its as illustrated in Figure 2, and since the members are of a softer material than the fittmg, the annular serrations or other imperfections in the bore will cooperate with the said end arrises and also cooperate and bite into the outer surfaces of the intermediate bearings l33 as indicated at [35 to increase the friction between the arm lit and fitting lid and yet allow for the relative rotational movement desired between them, and at the same time assist in preventing relative longitudinal movement therebetween. It is of course to be understood that insofar as the present invention is concerned it is not necessary to utilize the serrations or arrange the friction members so that the end arrises engage the bore. It will be evident that as a result of such compression, the inner surfaces of the end bearing portions 53% and 32 will intimately engage the intermediate neck 526 at longitudinally spaced areas remote from the shoulders 28 and I29 and spaced inwardly from the contact areas it? as exemplified in Figures 2 and 5. Due to the fact that each friction member engages the rough bore at three longitudinally spaced areas as compared to the two engaging the neck, the friction members are preferably held in substantially stationary positions so that the fitting and members may be rotated with respect to the arm. Obviously, the friction members may move relative to the fitting or arm. The intermediate bearing portions 633 of the friction members are deformed from their original shape so that the outer surfaces thereof conform to the curvature of the bore as depicted esi n in Figure 6, and preferably engage the latter over an area greater than any of the other contact areas.

It will be manifest that the assembled friction joints illustrated in Figure l are rotatable about the axis of the pintle and the mirror supporting arm, respectively. fhe frictional resistance in the joints is sufficient to permit the mirror mem her to be manually moved to and maintained in any selected operating position about either axis.

A new and unexpected result is achieved by the design and construction of the resilient members I33 in relation to radial frictional pressures Within the assembly in that the assembled friction joint may be rotated manually about the arm but cannot be disassembled except with the use of tools exerting axial pressures substantially in excess of manual pressures. Advantages of this unique friction joint reside in concealing the friction producing means and predetermin ing the extent or measure of friction so that no external manually controlled means are required for adjusting the friction. Simplicity of design and construction, durability, and economy of manufacture are additional attributes of the invention.

The universal friction joint illustrated in Figure 8 operates substantially in the same manner as the joint exemplified in Figure 2, but differs therefrom by modifying the arrangement so that an axial bore I3"! is provided in the upper extremity of a mirror supporting arm I38 with a shank portion I353 of a fitting Mil received in the bore I37. The fitting is provided with a portion I ll which cooperates with a hinge member of the type depicted in Figure 3. The shank portion of the fitting includes spaced bearing portions I42 and an intermediate reduced cylindrical neck portion I43, with the bearings I42 finding support in the bore for stability. It has been found desirable to make the neck portion and the friction producing members I44 here employed slightly longer for the reason that the cross-sectional dimensions of the parts are somewhat less than the construction illustrated in Figure 2. It will be noted that the exposed cylindrical portion of the shank I39 is preferably of the same diameter as the diameter of the arm so that it appears to be integral or a continuation of the arm. This particular arrangement also allows the mirror device to be rotated about the supporting arm and automatically held to any operating position desired.

The modification exemplified in Figure 9 operates in a manner similar to those above described and embodies substantially the same type of friction joint for the hinge as is used on the supporting arm. This construction includes a fitting I 55 provided with a bore for receiving the upper extremity of a supporting arm Hi6, and a generally spherical head portion Hi1 provided with a slot or notch receiving a tongue portion I48 formed on a hinge member I49 permanently secured to a mirror shell or backing. One side of the spherical head is provided with an aperture IEQ and the other side of the head with an aperture I5i coaxial with aperture ltiil. The tongue portion M8 is provided with an aperture I52 of a diametrical size substantially corresponding to and coaxial with the apertures E53 and IM. A pintle member I53 extends through the apertures referred to and one end of the pintle is preferably provided with longitudinally extending serrations or ridges I54 which are adapted to be forceably pressed into intimate engagement with the wall defining the aperture I5! so as to permanently lock the parts in assembly and prevent rotation of the pintle relative to the fitting. The pintle is provided with an intermediate reduced cylindrical neck por tion I55. A pair of friction producing members I56 are disposed about the neck portion and serve to increase the friction between the hinge member I59 carried by the mirror shell and the fitting I45. It will be noted that the friction producing members I58 exert radial pressures against pintle or pivot I53 whereas in the other modification illustrated in Figure 3, the lines of pressure are parallel to the axis of the pivot or rivet. As clearly illustrated the arm I46 is connected to the fitting I in the same way that arm H6 is connected to fitting M i.

Modifications and changes in details will occur to those skilled in the art without departing from the spirit and scope of my invention, but having set forth the objects and nature thereof, and having shown and described constructions embodying the principles of my invention, what I claim as new and useful and of my own invention and desire to secure by Letters Patent is:

I claim:

1. A rotatable friction joint comprising a female member provided with a cylindrical socket, a male member provided with a cylindrical plug seated in the socket, said plug having a reduced cylindrical portion terminating in spaced apart shoulders, a generally semi-cylindrical resilient member located between the shoulders and par tially embracing the reduced cylindrical portion of the plug, said resilient member having an expanded central portion resiliently bearing against an area of the inner surface of the socket, said resilient member also having end portions resiliently bearing against the reduced cylindrical portion at areas longitudinally spaced from the area engaged by the central portion, and said end portions being provided with marginal edges resiliently bearing against additional areas of the inner surface of the socket, the bearing areas serving to lock the members together and allow relative rotational movement between the female and male members.

2. A rotatable friction joint comprising a female member provided with a cylindrical socket, a male member provided with a cylindrical plug seated in the socket, said plug having a reduced cylindrical portion terminating in spaced apart shoulders, a pair of generally semi-cylindrical resilient members located between the shoulders and partially embracing the reduced cylindrical portion of the plug, each of said resilient members having an expanded central portion resiliently bearing against an area of the inner surface of the socket, each of said resilient members also having end portions resiliently bearing against the reduced cylindrical portion at areas longitudinally spaced from the area engaged by the central portions of the resilient members, and said end portions of said resilient members being provided with marginal edges resiliently bearing against additional areas of the inner surface of the socket, the bearing areas serving to lock the members together and allow relative rotational movement between the female and male members.

(References on following page) Fieferences Cited in the file of this patent UNITED STATES PATENTS Number Name Date Shriver Feb. 13, 1872 Dalzell Sept. 25, 1900 Wood Nov. 27, 1900 Waters Sept. 8, 1903 Neptune Jan. 6, 1914 Salfisberg Dec. 19, 1916 Dormandy Mar. 14, 1922 Moore July 18, 1922 Fitzgerald Aug. 8, 1922 Colley Feb. 9, 1926 Wilson Sept. 23, 1930 Mueller Mar. 3, 1931 Horton June 23, 1931 Zink Nov. 6, 1934 Gimbel June 4, 1935 Fox Dec. 1, 1936 Ritz-Weller Aug. 10, 1937 Number Number 8 Name Date Ritz-Woller Mar. 22, 1938 Putterman et a1. Nov. 29, 1938 La Hodny May 9, 1939 Lombard Oct. 17, 1939 Turner July 22, 1941 Murphy Nov. 18, 1941 Rueb Nov. 9, 1943 Poncher et a1. 1 Jan. 11, 1944 Duffield et a1 Mar. 21, 1944 Zeiler Apr. 22, 1947 Friedman Nov. 18, 1947 Lutolf Jan. 10, 1950 Chile Jan. 24, 1950 Case Apr. 4, 1950' FOREIGN PATENTS Country Date France Mar. 2, 1908 Germany July 12, 1928 

